DE2136405A1 - Process for protecting interfaces - Google Patents

Description

Dr. rer. near Horst pupil PATENT ADVOCATE

6 Frankfurt / Main 1, July 20, 1971 NkMasfraBe 52 Dr. Mo. / Vt

Telephone JttSll) 237220 Postal check account: 282420 FranMurtM. Bank account: 22ΚΏ389 Detutsdie Bank AG, Frankfurt / M.

1 Kiver Road

Free drive between the

Erfimdiuimg concerns service

from

WenstStrtaimg "by CSriiJimd! I3iiiaisseini dlelumtoarer materials, such as

strength ismd Etehinmadiuil in this, like a. B. fibers ÄlteimiMiTO ^ deimkristallem. ,, toradate miAt gams the expected

It sfliarde g'efmamnfem that a Meaktiom swiseliem the "ii üiHid der Qinuunidiiüiiasse toei fcohierem Tefflnperattüpeii the ^ first srlkmmg 'is made up of its strength · • fass these parts ¥ effeiimigem the same feei bucket

ϊίκ. eliie EsmiervfulijnssefcjEe ¹ Iteaükifeioint with the e-imi iiiilffidiWsfeifflaBzia toese & pMimkeim. It w / 'tre

10S88S / 1SS3

Ileher and more convenient, the melted material with the reinforcing Eies chilis sera, to water, but the increased temperature {and possible the greater mobility of the molten metal) increases the reaction rushes the reinforcements In elnee unbearable Motorcycle.

In another area, the "has been iahl materials Tut SEIE preßwerfczeuge by the possibility of reactions between. Sferkzeugmaterlal and the workpiece to be pressed are limited , whereby reactions never affect the surface of the tool and contaminate the surface of the memo.

It has been found, daJB> the application of reinforcing "fibers such as E. AluKlnlumoxldfasern or SllIcIuiiiicarbldraseinrL with;. A thin continuous Htoer & ug-won stable oxides _s as s B. ThorluiMoxid, Ceroxld or Yttrlujmoxld, the Elnfeam solctei * ¥ erstärknangen In (. SprundEiassen allowed kit to which they would otherwise react ip. Adversely, without a reaction taking place, so that they contribute a greater proportion of your theoretically predictable value to the solidity of the together-seefc ^ teini ZE ; or thermal decomposition ¹ JfOn ncetallorganlschen applied- These who drive produce thin Cz. B-. 25 hä Cl all— krolnch]) GlelchmialElge coherent homogeneous layers, which a good adhesion to the fibers and to the base assemblies read out. serve, has the idea that the sintered overlays are not large and monogamous, but rather have the same gap boundaries between their individual crystals; wmSL the Yerstärkiamgeia has a thick toe of the SrroJS.eEEOE "ci— miang of some tm (a few thousandths of an inch), so that> a sintered! · solids pot necessarily a foefcracfclfclfcllf the next amount of the day would be selime Inme—

elöieEi properties hide the music '. »iSEfäem» which may the ^ strengthening; The aim is - Welterfclim

■ ^ 1139886/1853

SAD ORIGINAL

the high temperatures required for sintering are harmful be for the Pasern.

The protection created by the oxide coatings according to the invention allows the base metal to be poured, with the undesirable reactions that are prohibited by the known processes, are prevented.

It has been found that the oxide coatings (or interface barriers, about a possibly more descriptive alternative | drawing to be used ^) that have been described, as well ceramic shapes such as B. aluminum oxide from reacting with hot materials containing metallic nickel, protection.

Similarly, such a coating has been found to protect molybdenum and tungsten from reaction with a molten alloy containing 80 % nickel and 20 % chromium, as well as alloys containing cobalt as a major component.

example 1

Monocrystalline alumina fibers were coated with yttria by sputtering in argon with a radio frequency discharge (1356 megahertz) at a voltage of about 150 volts. Short pieces (known as wires) were coated several times, stirring them together after each operation to ensure that all sides were exposed to the coating operation; in contrast, long fibers were rotated during only one coating operation, with the same result. Thereafter, to ensure a good bond with the base metal, the fibers were sputter coated with tungsten and then electroplated with nickel to a thickness of 25 µm (0.001 inches). These fibers were then embedded in an alloy of 80 % nickel and 20 % chromium by diffusion bonding in a vacuum at 1200 ^° C. under a pressure of up to 352 kg / cm ² (5000 psi).

109886 / 18B3 _MD οΓ ,, β, ΝΑΙ

Pasern obtained from such a composition by etching away exposed in the matrix show a typical tensile strength

2
over 21,100 kg / cm (300,000 psi) while Pasern that

embedded in the matrix without using the coating process described exhibit a tensile strength that is below 7030 kg / cm ² (100,000 psi).

Example 2

Silicon carbide fibers were coated as described in Example 1 with similar useful results.

Example 3

Tungsten and molybdenum fibers and wires and their alloys (such as molybdenum with additions of titanium and zirconium to prevent recrystallization of the molybdenum, also tungsten with an addition of thorium) can, as described in Example 1, treated with useful results.

example H

An alloy sold under the brand name "Haynes No. I88" is known, and the following compositions in weight i? Has: -. Cr W Ni C Si Mn Fe La Co

22 Ik 22 0.08 0.2 0.75 1.5 0.08 The remainder was used as a base material in the production of a diffusion bond according to Example 1 with equally good results.

Example 5

Molybdenum, tungsten and alumina fibers were cast in a molten alloy of 80 % nickel and 20 % chromium after being coated according to Example 1. It is noteworthy that alumina fibers are etxvas sensitive to thermal shock and cannot be successfully hard-cast in this alloy, but must be cooled slowly enough so that they can be mixed with the liquid

109886/1853

Alloy for a period of the order of 30 seconds can stay in contact, in which · pail a protection especially important is. Attempts were made before this invention » To cover aluminum oxide fibers with a coating of tungsten (which promotes wetting and the paser some protection before interacting with deia liquid metal), but the MoIf ram cover did not survive the long period of contact with the liquid metal.

Comparisons were made between the behavior of uncoated "molybdenum wires and yttrium oxide-coated molybdenum wires, which were hot pressed at 1200 C in a vacuum for half an hour in a matrix of 80% nickel and 20 % chromium. Metallographic sections of the interfaces between the wire and the matrix showed a clean interface between the coated wire and matrix, while the uncoated wire showed an alloyed area on the surface approximately J microns thick.

When such samples were further heated in Masserstoff to 1200 ⁰ C, the boundary between the coated wire was clean even after 100 hours of such a heating ,, increased during the alloyed like area on the surface of the non-coated wire to Ddcke as follows:

Heating time Alloy area thickness (hours) (micron)

IQ 20 ■

100 30

Similarly, a tungsten wire with an original thickness of approximately 550 µm was immersed in a molten alloy of 80% winding and 20 % chromium at 1 ^ 50 ° C. for 10 minutes. Yttrium oxide-coated wires showed no evidence of attack in the metal- * graphic section, while the diameter of the uncoated wire by dissolving in the

. 109886/18 53 sad

2136485

Base mass has been reduced to about 250 µm ; with other waits, about 3 / H of its mass was resolved. Uncoated molybdenum wires completely dissolved, while coated wires were unaffected.

While the heat of formation of the oxides, cerium oxide »hafnium oxide, lanthanum oxide, Thorium oxide and yttrium oxide are sufficiently high to make them stable and usable according to the invention, as they are revealed by tests, thorium oxide appears by its potential Radioactivity (and its higher density) is less desirable than the other oxides. For most uses, yttria will be used preferred.

Example 6

Hot press tools made from alumina and molybdenum have been sputter coated with yttria. Tools treated in this way separate easily from the finished workpiece and show no signs of chemical attack when they are used to hot-press a memory piece made of an alloy consisting of 80 % nickel and 20 % chromium at up to 1400 G. The oxide coating is preferably renewed after each operation because it is usually - at least partially - removed during the removal of the workpiece.

Uncoated tools used to react so violently with the material of the workpiece that the finished workpiece in some attempts to remove it from the mold to which it is passed adverse reactions was bound, was actually destroyed.

Publications ,, the process for the deposition of oxides of the group of interest by the decomposition of organometallic Revealing compounds of the metal are described in the following books:

"Special Ceramics" »published by P. Popper, Academic Press, Ifew York, 1965, a contribution by K.S. Mazdiyasni and CT. Lynch

: ■ 1Q3886 / 185 3 IAD ORIGINAL

"The Preparation of Alkoxides of Some Transition and Rare Earth Metals and the Formation of Powders and Coatings of Ultra-High Purity Zirconia ".

"Decomposition of Organo Metallic Compounds to Refractory Ceramics, Metals and Metal Alloys "edited by K.S. Maz ^ di yasni, University of Dayton Press, Dayton, Ohio, 1968, a contribution by M. Koch "Preparation of Large Quantities of Alkoxides and Their Decomposition to High Purity Submicron Refractory Oxides ".

109886/1853

Claims (5)

- 8 claims Method of protecting a plague body from reacting with a metal selected from chromium, cobalt and nickel that it can react with when in contact with them, characterized in that at the interface between said plague body and said Metal creates a uniform, continuous homogeneous layer of an oxide that is selected from the group consisting of yttrium oxide, cerium oxide, hafnium oxide, lanthanum oxide and thorium oxide. 2. The method according to claim 1, characterized in that the plague body is aluminum oxide. 3. The method according to claim 1, characterized in that the solid is silicon carbide. 4. The method according to claim 1, characterized that the said plague body is metallic Contains tungsten as the main component. 5. The method according to claim 1, characterized that said plague body contains metallic molybdenum as a main component. 109886/1853